Email marketing is alive and well—better than every before, in fact, thanks to an increase in HTML-friendly email clients and customers. However, if HTML email is still kicking, then egregious HTML email errors are running, stomping, crashing and charging into your inboxes with as much force as their marketing savvy counterparts. What follows are some of the worst email mistakes I've seen—bad messaging, poor design, unclean lists, you name it.

The wide variety of email marketing information, tools and services render these kinds of mistakes inexcusable in the business world. From self-serve HTML editor programs to full-service marketing firms, help is available for webmasters at every level. Imagine receiving some of these emails as you read through the "Worst Email Newsletter Mistakes" below; I've changed any identifying details to protect their innocent, yet misguided, creators, but you'll get the picture. If these glaring mistakes don't persuade you to take the time to do it right, it's time you went back to billboards and newspaper ads.

Unclosed Blink Tags

The blink tag has since been deprecated (and is long since dead and gone), but this mistake was so significant—not to mention annoying, distracting and down right obnoxious—that I still remember the frantic call from the customer as the blinking body of his email transfixed thousands of his customers into inactive zombies.

Too Many Different Font Faces, Colors and Sizes

Ah yes, the old, "if one is good and two is better, then a lot more must be best!" philosophy. Not so in email marketing. (or children, but that's a lesson for another day). Yes, by all means, make your headlines and subheads stand out with color and size differentiation, but don't go overboard. The old adage of Keep It Simple, Stupid applies here. As this client found out the hard way, too many competing fonts is too much for the eye to handle and potential customers simply delete the assault on their senses.

Excessive Use of Online Acronyms

I try (and occasionally succeed) very hard not to LMAO at some of the misguided corporate emails my clients fire off. I've seen some try to prove how "hip" they are by using as much internet slang as possible; others are just plain lazy. Either way, the end result is a garbled mess of letters that reads like some sort of code. Online acronyms aren't industry jargon just because you use the internet; your "business" email now reads like a junior high IM conversation, and it's annoying and unprofessional. Remember this and you'll never go wrong: DUMASS—Don't Use Misspellings or Acronyms in Serious Scripts.

Buying Lists from Spammers

This just screams amateur. Buying lists worked when email was still new and exciting, and Spam was just canned meat (come to think of it, nobody really wanted that kind either). Today, list-buying is essentially a complete waste of time and money, thanks to spam filters. I'm a geek, so I'll admit to scrolling through my junk email from time to time to see what gets dumped in there. My personal favorite? Spammy emails selling…spam filters.

Disregarding Your Audience

If you're sending out an email for a product or service, make sure your email list matches the target market. I've seen some half-rate startups completely ignore what their client is offering and sending out mass emails that only apply to about half the recipients (the mistake above may have contributed to some of these mass mailings as well). I had one such client come to me after failing to see an increase in leads for their breast reduction services. My advice? Focus your marketing efforts on women.

Never Updating Your Email Lists

This is a common mistake that runs the risk of annoying, and even insulting, your email marketing recipients, which leaves you open to some potentially damaging criticism. Yes, a recently successful dieter will be annoyed by your cookie-of-the-month club offers, but the family of the recently deceased on your email list will not be amused by your discounted life insurance plans. I laughed when I heard about this one, but I wasn't the one hurting my reputation. Update frequently and save yourself some embarrassment.

Accidentally Spam-like Subject Lines

Anyone who's been online for more than a minute knows the tell-tale warning signs of spam, and the subject line is usually the first clue. So, it stands to reason that if you give a legitimate email a subject line that sounds spammy, it will be treated as such. Well, one of my clients tried to "tease" his clients into opening his email promotion by promising to help increase the siz e of their..... portfolios. Well, we all know why it didn't work, but I had to delicately explain the message he was really sending with that subject line and suggested we take a more direct route.

Sending Out Unfinished Emails

What, is this like one of those cliffhanger episodes during sweeps? Or did a gorilla escape from the zoo and kidnap you before hitting "send"? I've been told that some people are unfamiliar with the email technology we have today and don't realize that "send" means "right now." Well, here it is, and next time you make me read a long, drawn out story or sales pitch, there better be a punchline or free offer at the end. Or else I'll…

Sending Out Repeat Emails

Computer glitches do exist, and human error is even more common, but do whatever you can to limit both of these if you want to be taken seriously as a business. I know I laughed after the second and third repeat emails for "Proven Memory Enhancement," but it stopped being funny around nine emails a day. You lose credibility as a company when you allow these kind of mistakes. Need me to repeat that? Bad business decision. Enough said.

Sending Private Emails to the Public

The oldest mistake in the book, magnified by instant and irreversible dissemination. It's very hard to do damage control when some cocky employee accidentally adds a customer email address to a missive about gullible customers falling for bogus promotions to cover up prices increases. Check and double check what you're saying and where it's going; a few quick forwards and your single slip-up could be all over the internet.